Hey everybody I've been getting a misfire in cylinder 3 I can't figure out. The cap and rotor are good and I just put in the new spark plugs but it didn't change anything. The only thing I did before it started misfiring was put in techron fuel injector cleaner. So I'm thinking the fuel injector over cylinder 3 is clogged or a bad spark plug wire. It's a 2000 civic lx with 242k miles. Thanks

 

sorry I forgot to mention that I did a compression check which was 170-180 for all cylinders. Now cylinder 3 and 4 are misfiring now. I just changed the fuel filter and it didn't change anything. No vacuum leaks and there is spark.

 

What brand of plugs did you use?

When was the last time the cap, rotor and wires were changed?

How are you determining you have misfires?

 

They are the Ngk spark plugs and I can't remember the mileage the cap and rotor was changed but it wasn't too long ago. All four contacts on the cap are still thick and the rotor looks solid still. First I counted the CEL blinks and then I verified the codes with a friends scanner.

I'm starting to lean towards the spark wires as they are AC delco brand and they are about 100k miles old. Haha.

 

So buy a spark tester, see if you're getting spark on that cylinder, and see what color spark you're getting on all 4.

 

Op, switch injectors out, see if the misfiring goes on that cylinder. Did the misfiring start randomly, or you been had it?

 

I pulled the spark wires out while the engine is running and put it against a bolt on the engine. Each wire put out a spark so it seems like each cylinder is getting spark. Also the engine ran rough each spark wire I pulled out.

 

Yeah I could do that but if I'm gonna do the work to take the fuel rail off to swap around injectors I minus well replace all 4. So I'm trying to keep that step last just before the fuel pump if it isn't fixed by then. The misfiring started last week.

 

Im not talking about replacing, i mean move the plugs around and see if the misfire moves with it. If it moves, then you know the injector itself is messed up.

 

So first off, that's a dangerous way to test for spark, and you were begging to fry a coil. Second, that doesn't tell us what color the spark is, which is equally as important as if it is or isn't there.

If you want to pursue the ignition system angle (which you should), and don't want to buy a spark tester (which you also should), try swapping the plug wires for cylinders 3 and 4, and see if the miss moves with the wire. If it does, then you've found your culprit. If it doesn't, then swap your spark plugs between cylinders 3 and 4, and see if the miss moves. If it does, once again, you've found your culprit. If it doesn't, then seriously, buy a spark tester and see what color the spark is on all four cylinders.

 

I've done that method to test for spark plenty of times. Just can't be stupid to do it around a fuel leak and if the spark were to hit you it only feels like a pinch. But back on topic, I did try swapping 3 and 4 wires and I got a 303 and 304 this time. I may have messed up the plug wire 4 since I had to stretch it to fit cyl 3. I just picked up a set of ngk wires. It was only $40 at advance auto parts anyways.

 

I was saying it would be like doing the job twice if one of the injectors was bad. Besides injectors hardly ever go bad so I doubt it's that.

 

NO they don't but they could clogged to ****. Which is why he said switch them around, and make a note of where they were before.

Also that is a bad way to test for spark but its up to you. Fuel has never cause an coil to go out, user error has about 80% of the time

 

Damn people... Lol op do as i say, and report back!

 

Well I attempted to switch injectors around and I ended up ripping up one of the damn o-rings. It's too late to run to the store to get an o-ring kit so ill just do it tomorrow.

 

My car is running like a champ now. It did end up being the fuel injectors so if you are having trouble figuring out a misfire and you replaced all ignition components then it's more than likely the injectors.

That's how you know we have some old *** civics when fuel injectors go bad.

 

Well they dont last forever.. theres a diy to clean yourself onhere somewhere for people reading this thread in the future.

 

It's also extremely cheap to send them to be professionally cleaned and flow tested. No one talks about it, but it doesn't hurt to have them done every 100k for a normal daily commuter.